Rick and the growing prison group of "The Walking Dead" face a troubling new problem if the ending of the Season 4 premiere is any indication.

Spoilers ahead if you haven't seen the season premiere.

The premiere ended with Carl's bud Patrick died in the shower and turned into a zombie. Guess whatever sickness he had doesn't mix well with the zombie virus everyone carries, because he went from feeling ill to being a dead man walking in no time flat.

That's not going to be good for the prison population. Lock up your cell doors people!

As you can see in the Episode 2 promo above for "Infected," zombies aren't just tearing at the prison fences.

"Walkers in D!" someone yells as they flee the prison. It interrupts a scene between Rick and Carl, who are tending to the pigs--did Patrick get swine flu?!--and discussing whether Carl should be allowed to have his gun again.

My guess? Carl gets his gun back because things look to be going south fast.

In the behind-the-scenes video below, cast members talk about how the prison group becomes more of a community this season, but I can't imagine that'll last for long. What do you think?